package main

import "fmt"

func modifyString(s string) string {
	res := []byte(s)
	for i := 0; i < len(res); i++ {
		if res[i] == '?' {
			index := 0
			var prev = byte(0)
			var after = byte(0)
			if i > 0 {
				prev = res[i-1]
			}
			if i < len(res)-1 {
				after = res[i+1]
			}
			c := byte('a' + index%26)
			for !(c != prev && c != after) {
				index++
				c = byte('a' + index%26)
			}
			res[i] = c
		}
	}
	return string(res)
}

func main() {
	fmt.Println(modifyString("?zs"))
}
